have a program where they, the city or state will errect the sound proof walls in neighboorhoods were traffic sounds will be an anoyance.
Before I sign any agreement, I would include in the agreement or contract that they, state, errect said fence or wall. Or the neighbor hood could ban together and petition the city council for this very same wall or fence to be errected.
I bet if whatever state your in, if you will drive along on some freeway or whatever your state calls them and when that road goes by a neighbor hood, you will see this very high wall. Actually its more for noise reduction than restriction of access.